Careful-your Google history is showing.

Airlines want to legalize coding that will enable them to tailor-make their flight prices based on what you type into any search engine.

Using computer cookies that keep track of previous interactions, databases of past purchases and technology that takes apart how a user arrived at a certain site, airlines can easily charge different rates for the same products simultaneously.

In a new USA Today article, Bill McGee examines the use of "yield management" in this potentially new way for the world's carriers to personalize every flight you book.

Adjusting flight, rental car and hotel prices based on peak times, days of the week, or seasons is called "dynamic pricing," and it's one thing-manipulating how much one pays based on their Internet activity is a whole other animal, and brings up questions of privacy and discrimination.

The yield management, McGee contends, is a certain form of prejudice-even though discounts are offered all the time for students, veterans and seniors, using an individual's buying history is too invasive of a practice.

In 2007, McGee conducted a test using a handful of computers and browsers to test this theory that industry and journalists claim have been a trend for more than a few years.

"In one case, we searched a major travel site for a fare from New York City to Sydney, Australia under identical...circumstances with two different browsers."

One browser was completely cleared of all cookies, cache and history. The other had a "robust history" of purchases for seats on planes.

"We found the cleared browser offered fares ranging from $1,770 to $1,950, while the second browser could only find a fare of $2,116."

Could this be a complete coincidence? Yes, no doubt-as a company spokesperson assured McGee after his test, there is no "user differentiation," used on these sites.

McGee warns bookers to "beware" all the same, as this growing trend could become more popular and potentially widespread as time goes on. 

"In the near future, we all may need to provide [extra] information simply to book a flight," he said.